Expert Perceptions of the Role of Biochar as a Carbon Abatement Option with Ancillary Agronomic and Soil-Related Benefits

Biochar is the solid remains of organic material that has been heated to > 350°C in an oxygen-limited environment, frequently intended to be mixed with soils. Biochar usually contains 80 – 90% stable aromatic carbon that is resistant to decomposition and mineralization (possibly for hundreds to thousands of years): it is, therefore, a potential way of removing carbon from the atmosphere for storage and has received considerable attention in the specialist media. Because the field is new there is no authoritative scientific assessment of the state-of-knowledge and its certainty. We therefore undertook an internet-based survey (n=145) to elicit expert opinion on the state-of-knowledge on biochar science and engineering. While expert opinion broadly supports the proposed benefits of biochar, the survey also identified a high degree of uncertainty attached to most of the knowledge-claims: more basic underpinning R&D will be necessary before policymakers will have confidence in implementing biochar projects.